Improving the Quality of Internal Surfaces of Cylindrical Parts by Plastic Deformation

The quality of internal cylindrical surfaces is of considerable importance in mechanical engineering, as it directly affects the functional performance, wear resistance, contact behaviour and service life of machine components. Conventional finishing operations, such as boring, reaming, grinding and honing, can improve geometrical accuracy; however, they do not always ensure the required improvement in the surface layer properties. In this study, the improvement of internal surfaces of cylindrical parts by roller plastic deformation was investigated. The main objective of the research was to evaluate the effect of roller burnishing on surface roughness and Brinell hardness as the principal indicators of surface quality. The internal surface of a cylindrical specimen was treated by a roller plastic deformation process, and the resulting surface condition was assessed in terms of the roughness parameter Ra and hardness HB. The preliminary results showed that the treated surface achieved a surface roughness of Ra = 0.8 µm and a Brinell hardness of HB = 205. These findings indicate that roller plastic deformation can be used as an effective chipless finishing method for improving the quality of internal cylindrical surfaces. The improvement is mainly associated with the plastic flattening of surface asperities, densification of the surface layer and work hardening caused by local contact pressure. The proposed method may be recommended for finishing bushings, sleeves, hydraulic cylinder elements and other cylindrical parts with functional internal surfaces.